Chemistry in the Community
Unit 2: Objectives 1 – 4 Review
Name
Period
Objective 1: Read and express information given in chemical formulas.

Determine the number of each atom present in acetaminophen (C8H9NO2).
C–
H–
N–
O–

Determine the number of each atom present in sulfuric acid (H2SO4).
H–
S–
O–

Determine the number of each atom present in iron (III) nitrate (Fe(NO3)3).
Fe –
N–
O–

Determine the number of each atom present in two sucrose molecules (C12H22O11).
C–
H–
O–

Determine the number of each atom present in three ammonia molecules (NH3)
N–
H–
Objective 2: Classify matter as a pure substance or a mixture.

List the symbols for the following elements:
a. Iron
b. Sodium
c. Antimony
d. Tungsten

Identify the difference between a mixture and a pure substance.

How does a compound differ from a mixture?

Identify each substance below as an element, compound, homogeneous mixture, or heterogeneous mixture.
a. Gold
b. NaCl
c. Fe
d. O2
e. Salt water
f.
Oil and water
g. Air
h. Vegetable soup

Matter may be subdivided into elements, compounds, heterogeneous mixtures, and homogeneous mixtures.
Describe one material found in your household that belongs to each category. Support your answer.
Element:
Compound
Heterogeneous mixture
Homogeneous mixture
Objective 3: Distinguish between chemical and physical changes, as well as chemical and physical properties.

Describe the difference between chemical and physical changes.

Use the following statements to distinguish between chemical and physical properties:
a. Lead is a dense, gray metal. When exposed to air, lead will form compounds with oxygen.
b. Methane is a very combustible gas with a low boiling point.

Identify each property below as either a chemical or physical property of that substance.
a. Aluminum bends easily.
b. Copper(II) sulfate dissolves in water.
c. Magnesium burns in air.
d. Gold jewelry is unaffected by perspiration.
e. Baking soda is a white powder.
f.
Fluorine is a highly reactive element.
g. Water boils
h. A match burns
i.

Food spoils
List one piece of evidence you expect to see that indicates a chemical reaction is taking place in each of the
following situations.
a. A slice of bread gets stuck in the toaster and burns.
b. An unused carton of milk is left on a kitchen counter for two weeks.
c. Wood burns in a campfire.
Objective 4: Balancing chemical equations.

2 Sr(s) + O2(g)  2 SrO(s)
Use the equation to answer the questions.
a. What is the physical state of strontium?
b. What is the coefficient of strontium oxide?
c. What is the subscript of oxygen?
d. How many reactants take part in this reaction?

Explain why subscripts should never be changed when balancing a chemical equation.

Balance the following equations:
Fe(s)
+

NH4NO3(s)
COCl2(g)
Sn(s)
+
+

O2(g)
Fe3O4(s)
N2O(g)
+
H2O(g)
H2O(l)

HCl(aq)
NaOH(aq)

Na2SnO2(aq)
+
CO2(g)
+
H2(g)